<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<script type="text/javascript">
	var a=1;  //定义整型变量a
	document.write("数值类型a="+a+"<br/>");
	var b=1.2;  //定义变量b
	document.write("数值类型b="+b+"<br/>");
	var c="你好";  //定义字符串类型变量c
	document.write("数值类型c="+c+"<br/>");
	var d=true;   //定义布尔类型变量d
	document.write("数值类型d="+d+"<br/>");
	
	var e;  //表示变量e不含有值，为undefind;
	document.write("变量不含有值e="+e+"<br/>");
	var f="你好啊";
	document.write("字符串变量f="+f+"<br/>");
	f=null;  //将字符串变量f置空
	document.write("置空变量f="+f+"<br/>")
</script>
</body>
</html>